package PTA2.ti21;

/**
 * @author Lenovo
 */
public class Main {
    public static void main(String[] args) {
        double sum=1.0-1.0/3.0+1.0/5.0-1.0/7.0+1.0/9.0-1.0/11.0+1.0/13.0;
        double PI=4.0*sum;
        System.out.println(PI);
    }
}
